Electrical instrument.



C. T. ANDERSON.

ELECTRICAL INSTRUMENT.

APPLICATION FILED Aue. I4. I9I1.

LBQ., Patented Novflv), 1918.

tiran spaans raras ernten.

CHARLES T. ANDERSON, 0F EDGEWOOD BOROUGH, PENNSYLVANIA, ASSIGNOR T0 THE UNION SWITCH & SIG-NAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPO- RATIQN 0F PENNSYLVANIA.

ELECTRICAL INSTRUMENT.

Speoicaton of Letters Patent. Patented NGV, 199 3913@ Application filed August 14, 1917. Serial No. 186,162.

To all whom t may concern.'

Be it known that I, CHARLES T. ANDERSON,

`One object of my invention is the provi-v sion of means for keeping the fingers of such a group in alinement. The invention is particularly well adapted to electrical relays, and I will describe it as applied to such, although it is understood that the invention is not limited to such application.

I will describe one form of device embodying my invention and will then point out the novel features thereof in the claim.

In the accompanying drawings, Figure 1 is a view showing in front elevation a portion of a relay including one form of device embodying my invention. Fig. 2 is a view showing in end elevation the portion of the relay and the device shown in Fig. 1.

Similar reference characters refer to similar parts in each of the views.

Referring to the drawing, It designates a portion of a relay which, as here shown, comprises two windings W and W', two polepieces l? one for each winding, and an armature A pivotall mounted in nonmagnetiz able brackets attached to the pole-pieces. The armature A carries a group of contact fingers F, which fingers are adapted to engage stationary contact blocks B when armature A is in the attracted position. As best shown in Fig. 2, each contact finger F comprises a relatively rigid arm 10 secured to but insulated from the armature by means of insulating studs K. One end of the bar 10 is bent in the form of a V, and secured to the free end of this bent portion is a contact spring-11, the outer end of which coacts with the corresponding fixed block B. It is understood that the arm 10 and the spring 11 are of electro-conductive material.

@ne important requirement of a relay, especially of a relay used in railway signaling, is that the electrical resistance of each contact, that is, the resistance between the nger F and the block B, shall be a minimum value. This means that the pressure between the two must be a predetermined value and that the finger must be properly alined so that it exerts a uniform pressure against the block throughout the length of the contacting edge of the finger. This adjustment is secured, when the relay is manufactured, by bending arm 10 or spring 11, or both, but such adjustment may not be permanent because, after long continued use, the parts of' the contact finger may become distorted or v bent.

To avoid such distortion of the fingers, I provide means for vrigidly connecting all of the fingers F so that each Enger is permanently held in the position of its original adjust-ment. As here shown, this means is in the form of a clamp H 'comprising two coextensive rigid strips 13 of insulating material, which strips are provided at spaced intervals with registering openings to receive bolts 141 for clamping the strips together. As shown, the clamp H is of suiicient length to embrace the springs 11 of all of the contact lingers F, the strips being arranged upon opposite sides of the springs while the bolts extend through the strips at points between the fingers, as best shown in Fig. 1.

In constructing the relay, all of the parts shown in the drawing, except the clamp H, are first assembled, and each finger F is then adjusted so that it is properly alined with respect to its block B and so that it bears against this block with the desired pressure when the armature is in the fully attracted position. The strips 13 of the clamp H arc then arranged on opposite sides of the springs 11, and the bolts 14 are tightened, thus securely clamping the springs between the strips. The clamp is preferably located as nearly as practicable to the contacting edges of the springs.

It will be -clear from the foregoing that after the contact fingers are thus adjusted and clamped, no one finger in the group can become distorted, nor can any one finger become bent out of alinement with respect to the remaining fingers in the group. In'other Words, by means of the ciamp H the original contact pressure and ahnement of the ngers, and so the original contant resistance,

are preserved throughout thevlife of the rela Aithough Ihave shown and described o nly one form of device embodying my mvention, it is understood that various changesI and modifications may be 'made therein v vlthin the scope of the appended clalm Without departing from the spirit and scope of my invention. n

I claim 1s:

An electrical instrument comprising a movable contact operating member, a' group of contact fingers each attached adjacent one end to said operating member, and means 20 for clamping said ingers together adjacent their other ends.

In testimon whereof I afHx my signature Having thus described my invention, what 15 in presence o two witnesses.

CHARLES T. ANDERSON. Witnesses: A. HERMAN WEGNER,

FAI GLASGOW. 

